1. Field of the Invention
The present invention relates to an electronic control unit for use in an automotive vehicle, and more particularly to a casing containing the electronic control unit therein.
2. Description of Related Art
An electronic control unit (referred to as an ECU) for use in an automotive vehicle is composed of a case having a bottom opening, a bottom cover closing the bottom opening and a circuit board contained in an inner space formed by the case and the bottom cover. Side stays are provided at both sides of the bottom cover so that the ECU is mounted on an automotive vehicle via the side stays.
FIG. 7 shows a perspective view, components being separated, of a conventional ECU 50. An ECU casing is composed of a case 51 and a bottom cover 53 closing a bottom opening of the case 51. A circuit board 52 having electronic components thereon is contained in the casing. The case 51, the bottom cover 53 and the circuit board 52 are connected together by common screws 54. Side stays 55 having mounting holes 56 are provided at both sides of the bottom cover 53. The ECU 50 may be directly mounted on a vehicle using the side stays 55, or using a separate bracket connected to the side stays 55.
In an automated line for mounting the ECU on the vehicle, plural ECUs 50 are placed on a conveyer passage 60 as shown in FIG. 8, and they are automatically picked up one by one by a robot arm or the like. When the ECUs 50 are positioned on the conveyer passage 60 in an upright posture (placing one sidewall on the conveyer belt 61, as shown in FIG. 8), it is required to make a proper space between conveyer sidewalls 62 and the ECUs 50. If the space is too large, the ECUs 50 fall on the conveyer belt 61, or the ECUs are not correctly aligned on the conveyer passage 60. On the other hand, if the space is too narrow, the ECUs 50 cannot be smoothly conveyed because sidewalls of the ECUs 50 contact the conveyer sidewalls 62, resulting in a conveyer halt at the worst case.
Further, side stays 55 formed at both sides of one ECU 50 may overlap the side stays 55 of another ECU 50 when ECUs are consecutively conveyed with no space therebetween, as shown in FIG. 8. If this happens, the ECUs 50 contact the conveyer sidewalls 62, thereby being stopped in the conveyer passage 60. The same problem may occur in a conveyer passage in which the ECUs 50 are conveyed in a flat posture.
Another problem in the conventional ECU resides in a mechanical strength of the side stays 55. Since the side stays 55 of the conventional ECU 50 are formed by simply extending the bottom cover 53 in a flat shape, as shown in FIG. 7, its mechanical strength is not sufficiently high to endure high vibration of an automotive vehicle. When the ECU 50 is mounted on a portion where a high vibrating force is imposed, the side stays 55 may be broken.
The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an ECU which is smoothly carried by an automated conveyer system. Another object of the present invention is to provide an ECU which has mounting stays having a sufficient mechanical strength to endure a high vibrating force of an vehicle.
The ECU is substantially box-shaped and is composed of a case having a bottom opening, a bottom cover closing the bottom opening and a circuit board having electronic components mounted thereon contained in a space formed by the case and the bottom cover. The bottom cover includes a pair of side stays for mounting the ECU on an automotive vehicle. The side stays extend to both sides of the bottom cover, and each side stay includes a bent portion bent upward from a bottom plate of the bottom cover.
The ECUs are placed on a conveyer belt in a conveyer passage, taking an upright posture or a flat posture, so that the bent portion of one ECU directly faces the bent portion of another ECU. Since the bent portions abut one another when ECUs are conveyed in contact with each other, the side stays do not overlap one another. Therefore, the ECUs are smoothly carried by the conveyer without causing jam or halt in the conveyer passage. In most cases, the ECUs are placed on the conveyer belt in an upright posture. In this case, it important to make the height of the bent portion larger than a difference between the width of the conveyer passage and the height of the ECU to prevent overlapping of the ECUs in the conveyer passage. The maximum height of the bent portion may be limited not to exceed the height of fringe walls of the bottom cover, so that plural bottom covers can be stacked up in an assembly process of the ECU.
To enhance mechanical strength of the side stay, a first rib perpendicularly extending from the side of the bottom cover is formed on the side stay. The first rib is also utilized to connect the bottom cover to the case at a right position. In addition, a pair of second ribs are formed along both sides of the bottom cover. The second ribs are positioned inside the ECU when the bottom cover is connected to the case to prevent dusts or foreign particles from entering into the ECU. The bent portion of the side stay may be eliminated if it is not necessary, and only the first rib and/or the second rib may be formed to enhance the mechanical strength of the side stay, so that the side stay is able to endure a high vibrating force of an automotive vehicle.
Other objects and features of the present invention will become more readily apparent from a better understanding of the preferred embodiment described below with reference to the following drawings.